Tap water drunk by up to 40million Americans may be raising their risk of a rapidly growing cancer, a study suggests.
Researchers at Texas A and M University compared kidney cancer rates in 240 Texas counties to arsenic levels in the water in public and private water systems.
They found people with high levels of the toxic mineral in their water had a 22 percent higher risk of the cancer. Even low levels the FDA considers safe were linked to a 6 percent increased risk.
Arsenic is a toxic substance found in rocks that enters groundwater when these erode. It can also be used in pesticides, and then washed into groundwater by rain.
In the body, it can be absorbed into the blood and travel into cells — causing damage to their DNA and raising the risk of cancer.
The results come as kidney cancer rates continue to surge in the US.
In 2010, it was behind 54,000 cases in the US every year. But in 2021, it was behind 68,000 cases — and was the ninth most common cancer in the nation.
Rates are rising by about 1.2 percent every year, data shows, alongside upticks of other cancers, including of breast and colon cancer in young people. This year was the first on record the American Cancer Society said 2million people would be diagnosed with the disease.
The above map, published in 2017, shows estimated arsenic levels in water from private wells across the US
The above map shows arsenic levels in public drinking water by county across the US. It is dated to 2006 to 2011
The uptick has happened at the same time as smoking rates, which also raise the risk of kidney cancer, have continued to decline.
Experts have previously suggested the uptick may be down to rising obesity rates or better imaging tests.
Other products also contain arsenic in low levels, including apple juice, apples, pears and grapes — and even white wine, according to some studies.
Dr Taehyun Roh, an epidemiologist from Texas A and M who led the latest study, said: ‘Some public water systems are poorly managed and could expose customers to arsenic, but the 40million people in the United States who rely on private wells are particularly vulnerable.’
Of the 40million, estimates suggest up to 2.7million are using private wells that contain more than 10ppb (parts per billion) of arsenic.
Wells in Nevada, Washington, and California, are most likely to contain the chemical.
Millions using public water systems are also exposed to high levels of arsenic, with a previous study by Consumer Reports finding eight percent of samples it tested from across the country had arsenic levels above 10ppb.
But the study found even 5ppb were linked to an increased risk of cancer.
The FDA says that the safe limit for arsenic is levels that do not exceed 10ppb.
The above shows kidney cancer cases by year in the US, according to the CDC
And this shows the kidney cancer case rate by year in the US, which accounts for shifts in population size. There is a dip in 2020 and 2021 during the Covid pandemic, when people were steering clear of the hospital
In the study, published in the journal Environmental Pollution, the researchers analyzed data from 28,896 cases of kidney cancer among those aged 20 years old recorded between 2016 and 2020 in Texas.
Data was adjusted for cancer risk factors such as obesity, smoking and diabetes, and other variables like pesticide density, income and heart disease rates.
The results also showed that every time the arsenic level in water doubled, the risk of suffering from the cancer was increased by four percent.
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Dr Roh added: ‘This study suggests that even low-level arsenic exposure in drinking water may be associated with an increased risk of kidney cancer.
‘This aligns with previous research indicating an association between this exposure and lung, bladder and skin cancers.’
The kidneys are responsible for filtering the blood for waste products and toxic substances, including arsenic.
Scientists say that exposure to arsenic over long periods, such as via drinking water, can cause damage to accumulate in the kidneys — leading to the cancer.
Early kidney cancer often doesn’t cause any symptoms, but in more advanced stages it can trigger warning signs such as blood in urine, lower back pain on one side and a loss of appetite.
Nearly two out of every three patients has their kidney cancer diagnosed at stage one or two, when the tumor has not spread in the body. And nearly one in every five has it diagnosed by stage three, when the cancer has spread to nearby tissue.
Overall, 77 percent of those diagnosed with kidney cancer live for more than five years after their diagnosis — a rate that has improved over time even as cases have risen.
It comes amid warnings over other substances in tap water to avoid, including PFAS.
